SDLC Context Agent - Add project-level setting part 1 (backend)

What does this MR do and why?

Implements the backend part of the SDLC Context Agent project-level setting (https://gitlab.com/gitlab-org/gitlab/-/work_items/611376).

Query Plan

The query plan in console.postgres.ai can't be generated yet, because the column doesn't exist yet in DB Lab to test against. However, the scope follows the exact same pattern as the existing with_duo_sast_fp_detection_enabled and with_duo_sast_vr_workflow_enabled scopes.

The raw SQL for the new with_duo_vulnerability_context_analysis_enabled scope:

SELECT "project_settings".* FROM "project_settings" WHERE (duo_vulnerability_context_analysis_enabled IS TRUE);

References

• Main epic https://gitlab.com/groups/gitlab-org/-/work_items/21005+
• Closes part 2 of the issue https://gitlab.com/gitlab-org/gitlab/-/work_items/611376+
• Frontend part will be done in: Draft: SDLC Context Agent - Add frontend toggle... (!249818 - closed)

Screenshots or screen recordings

N/A. This is a pure backend change. The frontend will be implemented in a follow-up

MR acceptance checklist

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